A resonance coupler according to one aspect of the present disclosure includes first resonance wiring and second resonance wiring. The first resonance wiring includes first open loop wiring, first input/output wiring extending outwardly from a first connection portion of the first open loop wiring, and first stub wiring extending inwardly from a second connection portion of the first open loop wiring. The second resonance wiring includes second open loop wiring, and second input/output wiring extending outwardly from a third connection portion of the second open loop wiring. The first stub wiring includes a first connection end connected to the second connection portion and a first open end on an opposite side. A wiring length from the first connection portion to the first open end is one-quarter of a wavelength of an nth-order harmonic of a radio-frequency signal, where n is an integer not less than 2.